.icon {
  position: relative;
  overflow: hidden;
  display: inline-block;
  color: #fff;
  text-decoration: none;
  line-height: 50px;
  font-size: 12px;
  font-family: sans-serif;
}

.icon:nth-child(2) { background: salmon; }
.icon:nth-child(3) { background: gray; }

/**
 * The "shine" element
 */

.icon:after {
  animation: shine 1.5s infinite linear alternate;
  content: "";
  position: absolute;
  top: -110%;
  left: -210%;
  width: 200%;
  height: 200%;
  opacity: 0;
  transform: rotate(30deg);
  
  background: rgba(255, 255, 255, 0.13);
  background: linear-gradient(
    to right, 
    rgba(255, 255, 255, 0.13) 0%,
    rgba(255, 255, 255, 0.13) 77%,
    rgba(255, 255, 255, 0.5) 60%,
    rgba(255, 255, 255, 0.0) 100%
  );
}

/* Hover state - trigger effect */


/* Active state */

.icon:active:after {
  opacity: 0;
}

@keyframes shine{
  to {
    opacity: 1;
    top: -30%;
    left: -30%;
    transition-property: left, top, opacity;
    transition-duration: 0.7s, 0.9s, 0.5s;
    transition-timing-function: ease;
  }
}